The present invention relates to an induction fluid supply unit for an induction exhaust apparatus and particularly such apparatus for ventilating of an enclosed area.
Exhaust hoods are widely used to exhaust contaminated air from an enclosed area such as a restaurant kitchen area, an industrial work area and the like. The exhaust air is preferably filtered to remove certain foreign products such as grease prior to discharge of the air or other fluid from the exhaust apparatus. Highly efficient exhaust apparatus has been developed wherein an induction air jet or stream is directed through an exhaust hood and into engagement with a filter. The induction air stream serves to induce the movement of the contaminated air from the enclosed area into the hood. The slot structure is important to maintain a smooth, turning characteristic which contributes to efficient and effective operation and functioning of the induction air stream. U.S. Pat. Nos. 3,978,777 and 4,047,519 which issued to Louis Nett disclose particularly effective and efficient exhaust hood apparatus of the inducted air stream principles and which have been widely used in restaurant kitchens and the like. The patents disclose a unique air slot having a curved bottom wall to form the induction air stream. The induction air stream in the above apparatus is untempered exterior air. Untempered air of course significantly minimizes the load on the heating and cooling systems for the enclosed area within which the hood is located.
As more fully disclosed in the above patents, the exhaust apparatus includes a filter within the hood which is set at a selected angle to the vertical. The air stream preferably engages the filter at substantially a right angle and has a velocity and mass which permits complete discharge through the filter so as to avoid spill or roll-off of the stream along the filter and vortexing within the hood which can disrupt the air pattern within the exhaust hood. Spill-over and/or vortexing can significantly reduce the effective operation of the exhaust hood and particularly interfere with the efficient removal of the contaminated air from the enclosed area. An original design and construction of an exhaust hood can of course properly locate the air stream source and the filter. However, many existing non-induction exhaust hood units are in place which could advantageously be modified to an induction exhaust principle. Further, various induction units could be improved by incorporating an induction air stream slot such as shown in the Nett patents. However, to provide a custom modification for each such hood is difficult and practically costly. Thus, the various existing exhaust hoods have the filters at widely different angular orientations. Consequently, it is impossible to provide a single supply unit with a properly located nozzle to provide an induction air stream of proper orientation for all such existing units. The conversion or retrofitting of existing units is particularly difficult where the highly advantageous slot structure having the curved bottom wall means is to be incorporated into the existing units.